JP2015050360A - Insulative coated powder for magnetic member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide insulative coated planular powder 2 for a magnetic member such as an electromagnetic wave absorber which is effective in blocking or absorbing electromagnetic waves in a frequency region of 1 MHz to 50 GHz.SOLUTION: Insulative coated planular powder 2 of the present invention comprises: metal powder 4 processed into planular forms; and an insulative coating film 6 deposited to the surface of the resultant metal powder 4. The metal powder 4 has an aspect ratio of 10-300. The coating film 6 includes polymerization products of titanium alkoxides. In the powder 2, the ratio of the thickness of the coating film 6 to the thickness of the metal powder 4 is preferably between 0.002 and 0.2 inclusive. In the powder 2, titanium alkoxides are preferably titanium alkoxide oligomers. In the powder 2, the coverage of the coating film 6 on the metal powder 4 is preferably 20% or more. Preferably, in the powder 2, the thickness of the coating film 6 is 1-200 nm; the coating film 6 is made of titanium oxide.

Description

  The present invention relates to an insulating coating powder for a magnetic member. Specifically, the present invention relates to an insulating coated flat powder for producing a magnetic member used for shielding or absorbing electromagnetic waves in a frequency range from 1 MHz to 50 GHz.

  Portable electronic devices typified by mobile phones, notebook personal computers, and tablet personal computers are widespread. Recently, with miniaturization and high performance, parts in a circuit are easily affected by noise generating parts such as semiconductor elements. In addition, it has been reported that electromagnetic waves emitted from portable electronic devices have an adverse effect on the body.

  In order to block electromagnetic waves emitted from semiconductor elements and portable electronic devices in a circuit board and prevent the influence of the electromagnetic waves, the electromagnetic wave generation source is wrapped with a magnetic member capable of shielding or absorbing the electromagnetic waves. . As this magnetic member, there is a case where a soft magnetic metal powder is blended with an insulator such as resin or rubber, and this is molded into a sheet shape or a ring shape. For this magnetic member, a soft magnetic metal powder that has been subjected to an insulating coating treatment may be used. Such a magnetic member includes an electromagnetic wave absorber, an electromagnetic wave absorbing sheet, and a magnetic sheet.

  The frequency of electromagnetic waves emitted from portable electronic devices tends to be higher. The actual state is that conventional magnetic members cannot sufficiently shield or absorb high-frequency electromagnetic waves. For this reason, various studies have been made on magnetic members effective in shielding and absorbing electromagnetic waves. Examples of this study are disclosed in Japanese Patent Application Laid-Open Nos. 2002-305395 and 2006-203233.

  Japanese Patent Application Laid-Open No. 2002-305395 discloses an electromagnetic wave absorber processed into a sheet shape. This electromagnetic wave absorber includes a powder obtained by subjecting the surface of a flaky soft magnetic metal powder to a phosphate treatment.

  Japanese Unexamined Patent Application Publication No. 2006-203233 discloses a radio wave absorber. This radio wave absorber is composed of a soft magnetic composite filled with metal soft magnetic particles having an electrically insulating layer made of molecules having an organic group.

JP 2002-305395 A JP 2006-203233 A

  In the electromagnetic wave absorber described in JP-A-2002-305395, the soft magnetic metal flake powder is selected from one or more selected from A) phosphoric acid, B) MgO, CaO and ZnO, and C). A phosphate film is formed on the surface of the powder by mixing with an aqueous solution or aqueous dispersion containing boric acid, draining the powder and drying. In order to form a film by immersing the powder in an aqueous solution (or aqueous dispersion) containing phosphoric acid, if a thin flaky powder is used, depending on the conditions, the powder may be dissolved in the phosphate treatment. There is.

  In the radio wave absorber described in the above Japanese Patent Laid-Open No. 2006-203233, application in the UHF band of 470 MHz to 770 MHz has been studied using metal soft magnetic particles having an electrically insulating layer made of a silane coupling agent. Yes. In this radio wave absorber, the insulation resistance is insufficient in the frequency region from 770 MHz to 50 GHz, and there is a possibility that the magnetic permeability decreases and the absorption characteristics deteriorate.

  An object of the present invention is to provide an insulating coated flat powder for a magnetic member such as an electromagnetic wave absorber effective for shielding or absorbing electromagnetic waves in a frequency range from 1 MHz to 50 GHz.

  The insulating coating flat powder for a magnetic member according to the present invention includes a flattened metal powder and an insulating film attached to the surface of the metal powder. The aspect ratio of the metal powder is 10 or more and 300 or less. The said film | membrane consists of a polymer of what contains titanium alkoxides.

  Preferably, in this insulating coated flat powder for a magnetic member, the ratio of the thickness of the film to the thickness of the metal powder is 0.002 or more and 0.2 or less.

  Preferably, in the insulating coating flat powder for a magnetic member, the titanium alkoxide is an oligomer of titanium alkoxide.

  Preferably, in this insulating coating flat powder for a magnetic member, the coverage of the metal powder by the coating is 20% or more.

  Preferably, in the insulating coated flat powder for a magnetic member, the thickness of the film is 1 nm or more and 200 nm or less. This film is made of an oxide of titanium.

  The magnetic member according to the present invention is formed using the above-mentioned insulating coating flat powder.

  In the insulating coated flat powder for magnetic members according to the present invention, the flattened metal powder is covered with an insulating film. This film is made of a polymer containing titanium alkoxides. Since titanium alkoxides polymerize at an appropriate reaction rate, an insulating film having a small thickness and a small thickness is formed.

As indices representing the performance of the magnetic member, there are magnetic permeability μ, real part magnetic permeability μ ′ and imaginary part magnetic permeability μ ”. Real part magnetic permeability μ ′ represents superiority or inferiority of electromagnetic wave shielding characteristics. "" Indicates superiority or inferiority of electromagnetic wave absorption characteristics. The magnetic permeability μ is expressed by the following formula using the real part permeability μ ′ and the imaginary part permeability μ ”. In the formula,“ j ”is an imaginary number ((j) ² = −1). is there.
μ = μ '+ jμ ”
In the present application, each of the magnetic permeability μ, the real part magnetic permeability μ ′, and the imaginary part magnetic permeability μ ″ is expressed by a relative magnetic permeability that is a ratio with the vacuum magnetic permeability.

  The metal-based magnetic material has a feature that the skin depth (a measure of the depth at which the generated eddy current can flow) is shallow, and the permeability does not decrease in a high-frequency region exceeding the Snoke limit, Higher frequency characteristics can be demonstrated. The characteristics are further demonstrated by flat processing. Further, the metal powder has a higher saturation magnetic flux density than the ferrite, and more easily exhibits the characteristics. However, since the metal powder has electrical conductivity, when the flat-processed metal powders come into contact with each other, the apparent thickness of the flat powder increases (the eddy current is generated in the portion corresponding to the total thickness of the contacted flat powders). Flowing). As the apparent thickness of the flat powder increases, the eddy current loss increases and the real part permeability μ ′ decreases. Furthermore, the imaginary part permeability μ ″ seen in the high frequency region is also lower than the real part permeability μ ′. In the powder of the present invention, an insulating film is formed on the surface of the metal powder. Even if a magnetic member is obtained from a material mixed with an insulator such as rubber, the coating prevents the metal powders from contacting each other, thereby suppressing the decrease in the real part permeability μ ′ due to the generation of eddy currents. According to the powder of the present invention, the real part permeability μ ′ of the magnetic member is improved as compared with the conventional powder. Further, the decrease in the imaginary part permeability μ ″ seen in the high frequency range is also suppressed. The For this reason, the magnetic member containing the powder of this invention is excellent also in the electromagnetic wave absorption characteristic in a high frequency region. According to the powder of the present invention, a magnetic member excellent in electromagnetic wave shielding characteristics and electromagnetic wave absorption characteristics can be obtained.

FIG. 1 is a cross-sectional view of an insulating coated flat powder for a magnetic member according to an embodiment of the present invention.

  Hereinafter, the present invention will be described in detail based on preferred embodiments with appropriate reference to the drawings.

  FIG. 1 shows a cross-sectional view of the insulating coated flat powder 2 of the present invention. Magnetic members such as an electromagnetic wave absorber, an electromagnetic wave absorbing sheet, and a magnetic sheet are formed using this powder 2. In the manufacture of the magnetic member, a base powder composed of an infinite number of powders 2 is prepared. This base powder is mixed with resin or rubber to obtain a composition. A magnetic member is formed using this composition. There is no restriction | limiting in particular in the shape of the formed magnetic member. Examples of the shape include a sheet shape, a ring shape, a cubic shape, a rectangular parallelepiped shape, and a cylindrical shape. In addition, there is no restriction | limiting in the method for mixing base material powder with resin or rubber | gum. Conventionally known methods are employed for this mixing method. There is no limitation on the method for forming the composition into a magnetic member. Conventionally known methods are also employed for this molding method. From the viewpoint of easy processing, processing aids such as lubricants and binders may be blended into the composition.

  The powder 2 includes a metal powder 4 and a film 6. This powder 2 is composed of a metal powder 4 and a film 6. The film 6 is attached to the surface of the metal powder 4. In the powder 2, a film different from the film 6 may be provided on the surface of the film 6. A film other than the film 6 may be provided between the metal powder 4 and the film 6.

  The metal powder 4 is obtained, for example, by pulverizing and flattening metal particles obtained by a gas atomization method or a water atomization method with a media stirring mill (attritor). Metal particles obtained by a mechanical process such as pulverization may be flattened and used as the metal powder 4. Metal particles obtained by a chemical process such as oxide reduction may be flattened and used as the metal powder 4. Alternatively, a powder that has been subjected to strain relief annealing after pulverization and flattening may be used as the metal powder 4.

  As described above, the metal powder 4 is flattened. The flatness of the metal powder 4 is expressed by an aspect ratio. In the present application, the aspect ratio is represented by the ratio between the length of the major axis of the metal powder 4 and the thickness of the metal powder 4. When the aspect ratio increases, the influence of the demagnetizing factor is suppressed. A large aspect ratio affects the real part permeability μ ′.

  In this powder 2, the aspect ratio of the metal powder 4 is 10 or more and 300 or less. As a result, the real part permeability μ ′ can be greatly improved in the high frequency region. When the aspect ratio is less than 10, the real part permeability μ ′ decreases in the high frequency region, and the electromagnetic wave shielding characteristics deteriorate. In this respect, the aspect ratio is preferably 50 or more. If the aspect ratio exceeds 300, the powder 2 may be broken when the powder 2 is mixed with resin, rubber, or the like. When the powder 2 is cracked, the aspect ratio is lowered, and it is difficult to process the powder while maintaining the characteristics. In this respect, the aspect ratio is preferably 200 or less.

  In the present application, the aspect ratio of the metal powder 4 is obtained as follows. The metal powder 4 is observed using a scanning electron microscope (SEM), and the position where the length is maximum in plan view is specified. This position is taken as the long axis, and the length L of this long axis is measured. The length L of the 50 metal powders 4 is measured, and the arithmetic average value Lav is calculated. This average value Lav is used as the length of the long axis of the metal powder 4 for calculating the aspect ratio. The metal powder 4 is embedded in a resin and polished, and the polished surface is observed with an optical microscope. The thickness direction of the metal powder 4 is specified, the maximum thickness tm and the minimum thickness tn are measured, and the average value ((tm + tn) / 2) of the maximum thickness tm and the minimum thickness tn is calculated. For 50 metal powders 4, an average value ((tm + tn) / 2) is obtained, and an arithmetic average value tav thereof is calculated. This average value tav is used as the thickness of the metal powder 4 for calculating the aspect ratio. By dividing the long axis length Lav by the thickness tav, the aspect ratio (Lav / tav) of the metal powder 4 is obtained.

  In this powder 2, the metal powder 4 is a soft magnetic material. Examples of the metal powder 4 include pure metals that do not contain other components, alloy powders made of an alloy steel to which alloy components have been added in advance, and those obtained by partially diffusing and adhering alloy components to the surface of pure metals or alloy powders. Can be used. Examples of the pure metal include iron (Fe), nickel (Ni), cobalt (Co), and gadolinium (Gd). As the alloy powder, boron (B), aluminum (Al), silicon (Si), germanium (Ge), which is an alloy of the above pure metals, or an alloy of the above pure metals or pure metals. , Titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), copper (Cu), zinc (Zn), zirconium (Zr), niobium (Nb), molybdenum (Mo) and tungsten (W) What added at least 1 sort (s) selected from the group which consists of is illustrated.

  Specifically, as the metal powder 4, pure iron powder containing no other components, Fe-3 mass% Si powder, Fe-6.5 mass% Si powder, Fe-3 mass% Si-2 mass% Cr powder, Fe- Examples include 5 mass% Al powder, Fe-9.5 mass% Si-5.5 mass% Al (Sendust) powder, Fe-50 mass% Co (permendur) and Fe-50 mass% Ni (Permalloy). “Mass%” is synonymous with mass%.

  The film 6 is insulative. In this powder 2, an insulating film 6 is formed on the surface of the metal powder 4. In a magnetic member obtained by mixing the powder 2 with an insulating material such as resin or rubber, the coating 6 prevents the metal powders 4 from contacting each other. As a result, a decrease in the real part permeability μ ′ due to the generation of eddy current is suppressed. According to the powder 2, the real part permeability μ ′ of the magnetic member can be improved as compared with the conventional powder. Since the powder 2 contributes to the magnetic flux converging effect of the magnetic member, the magnetic member using the powder 2 is excellent in electromagnetic wave shielding characteristics. Further, it is possible to suppress a decrease in the imaginary part permeability μ ″. For this reason, the magnetic member including the powder 2 of the present invention is also excellent in electromagnetic wave absorption characteristics in a high frequency region. According to the powder 2 of the present invention, the electromagnetic wave shielding characteristics and A magnetic member having excellent electromagnetic wave absorption characteristics can be obtained.

  As shown, the coating 6 covers the metal powder 4. In this powder 2, the film 6 is laminated on the metal powder 4. The film 6 is bonded to the metal powder 4. The film 6 covers the entire metal powder 4 or a part of the metal powder 4. From the viewpoint of electromagnetic wave shielding characteristics and electromagnetic wave absorption characteristics, the entire metal powder 4 is preferably covered with this film 6. This film 6 may be composed of two or more layers.

  The film 6 is made of a polymer containing titanium alkoxides. Specifically, the film 6 is made of a polymer of titanium alkoxides. In the present invention, titanium alkoxides are compounds in which at least one alkoxide group is bonded to a titanium atom in one molecule. In the present invention, the alkoxide group means a compound in which an organic group is bonded to oxygen having a negative charge. An organic group is a group made of an organic compound. The concept of titanium alkoxides includes a titanium alkoxide monomer, an oligomer formed by polymerizing a plurality of such monomers, and a compound at a stage prior to the production of titanium alkoxide (hereinafter also referred to as a precursor). It is. In addition, this membrane | film | coat 6 may be comprised from the polymer of what further contains components other than titanium alkoxides.

  From the viewpoint that a magnetic member having excellent electromagnetic wave shielding characteristics and electromagnetic wave absorption characteristics can be obtained, the ratio of the thickness of the film 6 made of titanium alkoxide to the thickness of the flattened metal powder 4 is 0.002 or more. 0.2 or less is preferable. If this ratio is smaller than 0.002, the insulation resistance is lowered and the magnetic permeability is lowered, or the metal powder 4 behaves as if they are in contact with each other, and the apparent thickness of the metal powder 4 is increased. The magnetic permeability decreases due to the influence of the coefficient. When this ratio is larger than 0.2, the film 6 becomes thick, the filling amount of the powder 2 decreases, and the magnetic permeability decreases. The thickness of the film 6 is a thickness T described later, and the thickness of the metal powder 4 is the thickness tav described above.

  Specific examples of the titanium alkoxide include titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, titanium tetrabutoxide, titanium tetra-2-ethylhexoxide, and isopropyltridodecylbenzenesulfonyl titanate.

  The powder 2 described above can be produced by various coating methods. Examples of the coating method include a mixing method, a sol-gel method, a spray dryer method, and a rolling fluidized bed method.

  The titanium alkoxides used in the present invention can be diluted with a solvent. The solvent is not particularly limited as long as it can dissolve or disperse titanium alkoxides. Examples of the solvent include acetone, methyl ethyl ketone, acetonitrile, methanol, ethanol, isopropyl alcohol, n-butanol, benzene, toluene, hexane, heptane, cyclohexane, chloroform, chlorobenzene, dichlorobenzene, ethyl acetate, ethyl propionate, and tetrahydrofuran. It is done.

  In this powder 2, titanium alkoxides are used for forming the film 6. Titanium alkoxides are polymerized on the surface of the metal powder 4 at an appropriate reaction rate as compared with alkoxides alone such as aluminum alkoxides and zirconium alkoxides. When the film 6 is made of a polymer of titanium alkoxides, the film 6 is made of an oxide of titanium. In the film 6 formed from titanium alkoxides, there are few cracks. Moreover, this film 6 is thin. The coating 6 can contribute to the improvement of the electromagnetic wave shielding characteristics and electromagnetic wave absorption characteristics of the magnetic member formed from the powder 2. According to the present invention, a magnetic member excellent in electromagnetic wave shielding characteristics and electromagnetic wave absorption characteristics can be obtained.

  When an oligomer of titanium alkoxide is used as the titanium alkoxide for forming the film 6, the titanium alkoxide is more suitable than when a titanium alkoxide monomer is used as the titanium alkoxide for forming the film 6. Polymerize at reaction rate. For this reason, generation | occurrence | production of a crack is suppressed more effectively in this membrane | film | coat 6, and the thinner membrane | film | coat 6 is obtained. This film 6 can contribute to the improvement of the electromagnetic wave shielding characteristics and electromagnetic wave absorption characteristics of the magnetic member. Therefore, in the present invention, an oligomer of titanium alkoxide is preferable as the titanium alkoxide from the viewpoint of improving an appropriate reaction rate and characteristics.

  The oligomer of titanium alkoxide is obtained by polymerizing a plurality of monomers of titanium alkoxide. In other words, the titanium alkoxide oligomer is formed from a titanium alkoxide monomer. The number of monomers constituting the oligomer affects the reaction rate of the titanium alkoxides when the film 6 is formed. From the viewpoint of an appropriate reaction rate, the number of monomers constituting the titanium alkoxide oligomer is preferably 4 or more, and more preferably 50 or less.

  In this powder 2, the coverage C of the metal powder 4 with the coating 6 is preferably 20% or more. As described above, the film 6 can contribute to the electromagnetic wave shielding characteristics and electromagnetic wave absorption characteristics of the magnetic member formed using the powder 2. From the viewpoint of improving characteristics, the coverage C of the metal powder 4 with the coating 6 is more preferably 30% or more. More preferably, the coverage C is 50% or more. Since it is most preferable that the entire metal powder 4 is covered with the film 6, a particularly preferable coverage ratio C is 100%. In the powder 2 shown in FIG. 1, the coverage C of the metal powder 4 with the coating 6 is 100%. This film 6 covers the entire metal powder 4.

  In the present application, a cross-sectional image of the powder 2 taken with a transmission electron microscope (TEM) is used to calculate the coverage C of the metal powder 4 with the coating 6. Specifically, 10 fields of view are photographed in a state in which the boundary between the metal powder 4 and the coating 6 can be confirmed from among the countless powders 2 observed by the TEM. In the photograph obtained by photographing, the length of the metal powder 4 covered with the film 6 (hereinafter also referred to as the coating length) and the length of the surface of the metal powder 4 are measured. In the present application, a numerical value representing a percentage obtained by dividing the coating length by the length of the surface of the metal powder 4 is represented as a coverage C.

  In FIG. 1, the double arrow T represents the thickness of the film 6. In the present application, the thickness T is represented by an average value of measurement values obtained from 10 images of a cross section of the powder 2 taken with a transmission electron microscope (TEM). When photographing, the powder 2 as a sample is adjusted so that a cross section of the powder 2 can be observed by focused ion beam (FIB) processing.

  The thickness T of the film 6 affects the electromagnetic field absorption characteristics and electromagnetic wave shielding characteristics of the magnetic member formed using the powder 2. When the thickness T is smaller than 1 nm, the insulation resistance of the molded magnetic member is lowered. In this case, the real part permeability μ ′ is lowered and the imaginary part permeability μ ″ seen on the higher frequency side than the real part permeability μ ′ is also lowered. From this viewpoint, the thickness T is 1 nm or more. When the thickness T is larger than 200 nm, the filling rate of the powder 2 contained in the magnetic member (the volume of the base powder composed of innumerable powders 2 of the resin or rubber in which these powders 2 are dispersed) In this case, the real part permeability μ ′ may be lowered and the imaginary part permeability μ ″ may be lowered. From this viewpoint, the thickness T is preferably 200 nm or less.

  Hereinafter, the effects of the present invention will be clarified by examples. However, the present invention should not be construed in a limited manner based on the description of the examples.

[Production of magnetic sheet (magnetic member)]
Prior to the production of the magnetic sheet, the powders of the examples shown in Tables 1 and 2 below were produced. In the production of this powder, a powder (10 kg) made of countless metal powders was prepared. The powder was processed with an attritor, and each metal powder was flattened. As the metal powder, Fe-3 mass% Si powder and Fe-9.5 mass% Si-5.5 mass% Al powder were used.

  Using a treatment liquid containing titanium alkoxides, a film was formed on the flattened metal powder to produce the insulating coated flat powder shown in FIG. The types of titanium alkoxides used for the preparation are shown in Tables 1 and 2 below. The titanium alkoxide oligomer used to form the film was prepared by adding an appropriate amount of a solvent to the titanium alkoxide monomer. Table 1 shows the case where Fe-3 mass% Si powder was used for the metal powder, and Table 2 shows the case where Fe-9.5 mass% Si-5.5 mass% Al powder was used for the metal powder.

  The base powder made of countless insulating coated flat powder obtained as described above is kneaded with an epoxy resin at a temperature of 100 ° C. using a small mixer to obtain a resin composition in which the powder is uniformly dispersed. It was. The volume ratio of the epoxy resin to the base powder was 5 to 2. This resin composition was hot-pressed for 5 minutes under the conditions of 4 MPa and 200 ° C. to obtain a magnetic sheet having a thickness of 0.1 mm.

[Evaluation of magnetic sheet]
With respect to the produced magnetic sheet, the real part permeability μ ′ and the specific resistance at a temperature of 25 ° C. and a frequency of 20 MHz were measured. The results are shown in Tables 1 and 2 below. The real part permeability μ ′ was measured using a product name “Vector Network Analyzer N5245A” manufactured by Agilent Technologies. The product name “DSM-8104” manufactured by Hioki Electric Co., Ltd. was used for the measurement of the specific resistance.

  Below, the powder in each example is demonstrated in detail.

[Examples 1-6, 11-12, 15-16, 19-24, 29-30 and 33-34]
Examples 1-6, 11-12, 15-16, 19-24, 29-30 and 33-34 use metal powder having an aspect ratio in the range of 10 to 300. The coating was formed from a titanium alkoxide monomer. The film thickness T, the ratio of the thickness T to the thickness tav of the metal powder (T / tav), and the coverage C of the metal powder by the film are as shown in Table 1-2.

[Examples 7-10, 13-14, 17-18, 25-28, 31-32 and 35-36]
Examples 7-10, 13-14, 17-18, 25-28, 31-32 and 35-36 use metal powder having an aspect ratio in the range of 10 to 300. The film was formed from an oligomer of titanium alkoxide. The film thickness T, the ratio of the thickness T to the thickness tav of the metal powder (T / tav), and the coverage C of the metal powder by the film are as shown in Table 1-2.

[Comparative Examples 1-2 and 6-7]
Comparative Examples 1-2 and 6-7 use metal powder having an aspect ratio of less than 10 or greater than 300. The film thickness T and the coating rate C of the metal powder by the film are as shown in Table 1-2.

[Comparative Examples 3-5 and 8-10]
The films of Comparative Examples 3-5 and 8-10 were formed from metal alkoxides other than titanium alkoxide. The film thickness T and the coating rate C of the metal powder by the film are as shown in Table 1-2.

[Comprehensive evaluation 1 (magnetic sheet using Fe-3 mass% Si powder)]
The following rating was performed based on the values of the real part permeability μ ′ and the specific resistance.
A: The real part permeability μ ′ is 12 or more and the specific resistance is 1.0 × 10 ⁵ Ω · m or more. B: The real part permeability μ ′ is 10 or more and less than 12, and The specific resistance is 1.0 × 10 ⁵ Ω · m or more. C: The real part magnetic permeability μ ′ is 9 or more and less than 10, or the specific resistance is less than 1.0 × 10 ⁵ Ω · m. D: The real part permeability μ ′ is less than 9. This result is shown in Table 1 below. Good in the order of A, B, C, D.

[Comprehensive evaluation 2 (magnetic sheet using Fe-9.5 mass% Si-5.5 mass% Al powder)]
The following rating was performed based on the values of the real part permeability μ ′ and the specific resistance.
A: The real part permeability μ ′ is 8 or more and the specific resistance is 1.0 × 10 ⁷ Ω · m or more. B: The real part permeability μ ′ is 7 or more and less than 8, and The specific resistance is 1.0 × 10 ⁷ Ω · m or more. C: The real part magnetic permeability μ ′ is 6 or more and less than 7, or the specific resistance is less than 1.0 × 10 ⁷ Ω · m. D: The real part permeability μ ′ is less than 6. This result is shown in Table 2 below. Good in the order of A, B, C, D.

As shown in Table 1, when Fe-3 mass% Si powder was used as the metal powder, the magnetic sheet using the powder of the example had a real part permeability μ ′ of 9 or more under the condition of a frequency of 20 MHz. Was realized. Furthermore, by using an oligomer of titanium alkoxide for forming the film, a real part permeability μ ′ of 12 or more and a specific resistance of 1.0 × 10 ⁵ Ω · m or more were realized. As shown in Table 2, when the Fe-9.5 mass% Si-5.5 mass% Al powder was used as the metal powder, the magnetic sheet using the powder of the example had a frequency of 20 MHz under the condition of 6 MHz. The above real part permeability μ ′ was realized. Furthermore, by using an oligomer of titanium alkoxide for the formation of a film, a real part permeability μ ′ of 8 or more and a specific resistance of 1.0 × 10 ⁷ Ω · m or more were realized.

  The insulating coating flat powder described above can be applied to various magnetic sheets.

2 ... Powder 4 ... Metal powder 6 ... Film

Claims (6)

It has a flat-processed metal powder and an insulating film attached to the surface of the metal powder.
The aspect ratio of the metal powder is 10 or more and 300 or less,
An insulating coated flat powder for a magnetic member, wherein the coating comprises a polymer containing titanium alkoxides.   The insulating coating flat powder for a magnetic member according to claim 1, wherein the ratio of the thickness of the coating to the thickness of the metal powder is 0.002 or more and 0.2 or less.   The insulating coating flat powder for magnetic members according to claim 1 or 2, wherein the titanium alkoxide is an oligomer of titanium alkoxide.   The insulating coating flat powder for a magnetic member according to any one of claims 1 to 3, wherein a coating rate of the metal powder by the coating is 20% or more. The thickness of the film is 1 nm or more and 200 nm or less,
The insulating coating flat powder for a magnetic member according to any one of claims 1 to 4, wherein the film is made of an oxide of titanium.   A magnetic member formed using the insulating coating flat powder according to claim 1.

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